In modern internal combustion engines, tensioning rails, which are supported via a pivot bearing provided on the engine block, are used for various applications, e.g. for the timing chain drive, and also for drives of ancillary units, e.g. of the oil pump and the air conditioning compressor. Whereas in a chain drive of the type in question, the associated guide rail is fixedly arranged at a specific position, where it ensures reliable guidance of the driving chain, tensioning rails are supported, by means of the pivot bearing provided on the engine block, such that they are pivotable relative to the driving chain so as to tension the driving chain in the chain drive with the aid of a chain tensioner. An increasing number of units to be driven in combination with an identically sized installation space or an installation space of reduced size leads to an increasing complexity of the engine and an increasing complexity of engine component mounting in the case of modern engines.
DE 44 37 926 C1 discloses a device for tensioning the chain of an internal combustion engine, in the case of which a tensioning arm for an oil pump chain is supported on a bolt fixed in the internal combustion engine, said bolt being also used as a point of support of a guide rail of the control drive. The guide rail of the timing chain drive and the tensioning rail of the auxiliary chain drive are here extended in length so as to unite the two points of support, which would otherwise be necessary, in one pivot bearing and so as to allow a joint support on an extended pivot bearing bolt secured in position on the engine block.
A combined tensioning and guiding device is described in DE 10 2004 014 486 A1, in the case of which a pivot pin is provided on an extension of the guide rail, the associated tensioning rail being pivotably supported on said pivot pin. In addition, the joint between the guide rail and the tensioning rail is provided with a lock against rotation.
Reference DE 10 2010 005 405 A1 discloses a mounting unit for a chain drive with a guide rail and a tensioning rail. The guide rail comprises two legs, which extend laterally in parallel to one another and the ends of which are provided with two spaced apart openings. The tensioning rail comprises a complementarily configured bearing sleeve, which is introduced in said openings and locked in position therein during operation.
The chain drive assemblies for internal combustion engines known from the prior art exhibit different mounting concepts with a fixed arrangement of the tensioning and guide rails to be installed, with a predetermined configuration, in a chain drive of an internal combustion engine. With respect to the increased complexity of internal combustion engines, the installation of such mounting units often necessitates the use of complicated constructions, since the possibilities of attaching them to the engine block become lesser due to the complexity of the engine. Hence, new mounting concepts for attachment parts and chain drives are necessary. The number of components or multifunctional components used should here be as small as possible, so as to allow an expedient utilization of such new chain drives and components in combination with a modern internal combustion engine.
Moreover, especially in the field of automobile industry, there is a high innovation pressure, which finds expression in continuous endeavors to improve and optimize components and their incorporation into internal combustion engines that get more and more complicated. Chain drives and tensioning rails are, in addition to the aspect that they are designed for special engines, mass products with respect to the high piece numbers for individual engines, such mass products necessitating a continuous improvement of the structural design and of the mounting efforts required.